[sz617896964]

Dear all,

I am trying to simulate the VIV of a circular cylinder at low Reynolds number (Re=100), so the case is 2D simulation (the boundary condition of front and back side is empty). The attached case is when reduced velocity is equal to 6, check the VIV situation. Also, it is only a y-direction problem and the linear spring is utilized. The mass ratio is equal to 1.27 and the damping ratio is equal to 0.05. The mesh should be fine as it does work when the circular cylinder is fixed.

If I considered the mass effect at the initial condition, I would give the initial length of spring to make sure the circular cylinder is static from the begining. For example, the mass is 1kg, and the stiffness of the spring is 1.1.I also set the anchor point is (0 20 0.5) and the refAttachmentPt is (0 0 0.5). Thus the restLength is 20-1*9.8065*1.1=11.085 to make sure the gravity is equal to the spring force at the initial condition. However, it does not work. When the simulation went around 7 seconds, the floating point exception error occurred, and I checked the centre of mass which was increasing during the period.

Also, I did another try to neglect the mass effect. I set the anchor point was the same as the refAttachmentPt is (0 0 0.5), which was the centre of mass point, and the restLength was 0. Then the centre of mass was decreasing during the period until floating point exception occurred.

I have no idea why this issue happened. I attach my case in the thread. If anyone could do me a favour to have a check, I will be much appreciated for that.

PS: The files in the constant folder are incomplete as the maximum size of the uploading file is limited.

Kind regards,
Ze